Antibiotiki i meditsinskaia biotekhnologiia = Antibiotics and medical biotechnology最新文献

Eremomycin, a novel antibiotic belonging to the group of cyclic glycopeptides is produced by an actinomycete designated INA-238. Biosynthesis, isolation, physico-chemical and biological properties of the antibiotic are described. Eremomycin is shown to be close to vancomycin. However, by its chromatographic and electrophoretic mobility, presence of chlorine in the antibiotic molecule and optic characteristics eremomycin differs from vancomycin. Eremomycin is less toxic than vancomycin whereas its chemotherapeutic activity in treatment of infections caused by gram-positive organisms is higher.

Kanamycin B content in kanamycin preparations was determined with column chromatography and PMR spectroscopy. It was shown that coincidence of the results obtained with both the procedures in analysis of the preparations subjected to additional recrystallization was satisfactory. With the use of nonrecrystallized preparations the admixtures interfered with the results in using the developed procedure.

Reaction to rapid intravenous administration (RIA) of rifampicin in a dose of 10 mg/kg was studied on 173 healthy dogs. Immediately after the first RIA of rifampicin there were observed vomiting and ataxia of various levels in 5.2 per cent of the animals. After the drug administration their arterial pressure (AP) lowered to 50-60 mm Hg. By the 9th-11th minute it restored to the initial level. A collapse-like condition was recorded immediately after rifampicin RIA in 2.3 per cent of the dogs with marked decreasing of their AP up to 15-20 mm Hg. Its restoration to the initial level was slow and required 35-40 min. It was noted that after the third consecutive RIA of rifampicin the observed reaction disappeared. Probably this was due to adaptation of the host to rifampicin intravenous injections. Mezaton is an efficient agent rapidly arresting the reaction within 1-3 min.

Comparison of sensitivity of 63 clones of R, S and M variants of Rhodococcus rubropertinctus 104 to 6 antibiotics showed that sensitivity of the variants was similar only to erythromycin. Their sensitivity to penicillin, streptomycin, chlortetracycline, rifampicin and actinomycin C was different. Still, they preserved similar regularity: M cells were the most sensitive and R cells were the most resistant. There was a 1.5-3 fold difference in sensitivity of R and M variants to the antibiotics. The number and rate of chlortetracycline absorption by R cells were lower than those of S and especially M cells which must condition their higher resistance to the antibiotic.

Experimental design was used in studying the effect of certain qualitative factors on rheological properties of antibiotic hydrogels. It was shown that water solubility of antibiotics and the procedure of their addition to gel bases were important in developing hydrogels. Scanning electron microscopy was used in comparative analysis of antibiotic hydrogels.

Distribution of genetic determinants of resistance to streptomycin, kanamycin, chloramphenicol, tetracycline, sulfanilamides and trimethoprim in strains of Salmonella isolated from studied. The majority of the resistant strains carried the genes of aminoglycoside-3"-phosphotransferase, type I aminoglycoside-3'-phosphotransferase, type I chloramphenicol acetyltransferase and type II dihydropteroate synthetase. Tetracycline resistance in the strains was often due to the class B tetracycline resistance genetic determinants. It was suggested that the resistance mechanisms controlled by these genes provided higher levels of resistance to the above drugs in Salmonella as compared to the other mechanisms. Plasmid resistance genes were detected in more than 90 per cent of the clinical strains and in 35 per cent of the sporadic strains of S. typhimurium. The antibiotic resistance of the Salmonella strains of other serovars was not as a rule controlled by the plasmid genes.

The effect of potassium orthophosphate on growth of the mycelium, its ATP contents and biosynthesis of the macrotetrolide antibiotic nonactin by Str. chrysomallus var. macrotetrolidi was studied. Direct dependence of the ATP contents in the mycelium on the amount of the phosphate added to the medium and consumed by the developing actinomycete was shown. Changes in the intracellular content of ATP depended also on the mycelium age. It was characterized by two peaks. Hemin was detected in the actinomycete mycelium. Its levels were sufficiently high and depended on the mycelium age and cultivation conditions, in particular on the phosphate content in the medium. Higher levels of nonactin biosynthesis were characteristic of the mycelium with lower contents of ATP, proteins and hemin. Intensive production of the antibiotic proceeded at the background of decreasing levels of ATP in the mycelium.